deadlock with truncate and foreing keys

[Alexey Nalbat <nalbat@xxxxxxxx>]

Hello.

I've encountered deadlock with first transaction updating information
field in the primary table, and second trasaction reloading secondary
table using TRUNCATE and INSERT. Here is simple example:

create table t1 ( id integer primary key, name text );
create table t2 ( id integer references t1 );
insert into t1 values ( 1 );
insert into t2 values ( 1 );

Then two concurrent transactions start.

/* 1 */ begin;
/* 1 */ truncate t2;
        /* 2 */ begin;
        /* 2 */ update t1 set name='foo' where id=1;
/* 1 */ insert into t2 values ( 1 );

Here we have deadlock.

ERROR:  deadlock detected
DETAIL:  Process 21581 waits for ShareLock on transaction 464; blocked by process 21619.
Process 21619 waits for AccessShareLock on relation 16456 of database 16385; blocked by process 21581.
CONTEXT:  SQL statement "SELECT 1 FROM ONLY "public"."t1" x WHERE "id" OPERATOR(pg_catalog.=) $1 FOR SHARE OF x"

When substituting TRUNCATE with DELETE, second transaction is not
waiting for first one, and there is no deadlock error. But I prefer to use
TRUNCATE because it is much faster. (In fact I use COPY instead of
INSERT to speed up reloading of secondary table.)

Is it bug? And if so, will it be fixed?

Thank you. Sorry for bad english.

-- 
Alexey A. Nalbat

Price Express
http://www.price.ru/
http://www.tyndex.ru/

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